Читать книгу Fundamentals of Fixed Prosthodontics - James C. Kessler - Страница 73

The incisal pin is adjusted for a 2-mm opening to accommodate the thickness of the interocclusal record. The articulator with the attached maxillary cast is inverted, with care taken to ensure that the centric latch is engaged. The centric relation interocclusal wax record is placed on the maxillary cast. The teeth should seat completely into the record.

The mandibular cast is placed into the interocclusal record, with care taken to ensure that the teeth are fully seated. There should be no contact between the maxillary and mandibular casts. The mandibular cast is removed, and the bottom and sides of it are soaked in a partially filled bowl of water for about 2 minutes.

The soaked mandibular cast is reseated into the interocclusal wax record. Some mounting stone is mixed to a thick, creamy consistency, and a mound of it is placed on the inverted bottom of the cast. Some mounting stone is applied to the mounting plate on the lower member of the articulator, which is hinged down into the soft stone on the cast until the incisal guide pin makes firm contact with the incisal guide block. The mandibular cast is stabilized by hand to keep it securely in the interocclusal record until the mounting stone sets (Fig 5-48). Rubber bands or sticky wax can also be used, but they are more likely to slip and produce a mounting error.

Fig 5-48 The cast is held in the interocclusal wax record until the mounting stone sets.

The casts and articulator are examined for the following:

 The condyle is located against the posterior and superior walls of the condylar guide.

 Both casts are completely seated in the interocclusal record.

 Mounting stone engages undercuts on both the base of the cast and the mounting plate.

When the mounting stone has set completely, the accuracy of the mounting is confirmed. The articulator is opened, the interocclusal record is removed, and the incisal guide pins are raised 1 inch. A 2-inch piece of no. 10 red-inked silk ribbon is placed between the posterior teeth on both sides. The teeth are tapped together lightly with the condyles against the posterior wall of the condylar guide, leaving red dots that represent the contacts at centric relation position, as described in chapter 4.

The pieces of 28-gauge green wax that have been stored in a cup are retrieved and lightly placed on the teeth of the maxillary cast. The accuracy of the mounting is confirmed if the red dots are visible through the perforations in the wax. If they are not visible, the procedure should be rechecked and the error corrected.

The casts and their mounting plates are removed from the articulator. Additional mounting stone is mixed to fill any voids between the casts and their mounting plates. The mounting stone is smoothed with a finger to give it a neat appearance. No stone should remain on the surface of the mounting plate that will contact the articulator frame. Both the dental technician and the patient form an impression of the dentist when they see these casts on the articulator, so it is important to make sure that it is a positive one.